1. Field of Invention
The invention relates to a power polarization beam combiner used in fiber network systems and, in particular, to a power polarization beam combiner made of highly dispersive material with a negative refractive index and its applications in fiber network systems.
2. Related Art
With the increase of local network systems in metropolitan areas, one is forced to increase the number of wavelengths in order to transmit a huge amount of information. Therefore, the CWDM transceiver and CWDM receiver become important. As the transmission distance gets longer, a higher optical transmission power is imperative. In particular, the use of the EDFA and the Raman amplifier requires a good power combiner. It is mainly because the laser power is insufficient for long-distance transmissions. Thus, a set of EDFA or the Raman amplifier is often installed every 40 km to enhance the laser power. Nonetheless, as the fiber distance gets longer, the number of laser amplifiers also increases. This inevitably increases the cost for fiber equipment and maintenance.
Moreover, conventional amplifiers, it is either EDFA or Raman amplifier, mainly combine beams of different polarizations within the transmissible wavelength range to increase the transmitted optical signal power. This results in huge sizes for the conventional power combiners.
The U.S. Pat. No. 6,188,819 discloses a wavelength division multiplexing (WDM) device designed using a photonic crystal with a normal refractive index. Although it is successful in reducing the device size, it cannot combine beams of different polarizations.